A five-game win streak by the 49ers is the only one among NFC teams currently longer than the Panthers (5-3), who have won four in a row and scored at least 30 points in each victory while limiting opponents to 15 or fewer.

Cam Newton's play has illustrated the nature of their season as a whole. He completed 57.5 percent of his passes with six TDs, five interceptions and a 78.4 passer rating in the team's first four games. During the win streak, Newton is completing 72.3 percent with seven TDs, two picks and a 109.8 rating along with three rushing touchdowns.

The surge may mean a longer leash for coach Ron Rivera, who entered the year on the hot seat after going 13-19 in his first two seasons.

"I think we can be a playoff team because of the things we've done and because of the way we're playing," Rivera said. "If we had played like this, consistent all the way through, who knows? We have a great opportunity and a challenge in front of us. The chances can be limitless. But we have to play that way. Just because we're doing it now doesn't mean it is automatic."

Carolina is a game behind New Orleans for the NFC South lead as the franchise seeks its first five-game win streak since a six-game run Oct. 3-Nov. 13, 2005. The Panthers went on to lose in the NFC championship game that year.

However, the current streak has come against teams with a combined 8-33 record. After facing the 49ers (6-2), the Panthers will host AFC East-leading New England and still have two meetings with the Saints looming.

"I think a lot of people are doubting us and what not," tackle Jordan Gross said. "But we know how good we are and we've just got to go out there every week and prove it."

San Francisco is coming off its bye week after building a wave of momentum, winning five in a row by a 174-61 margin after being outscored 56-10 in losses to Seattle and Indianapolis.

"Really a dramatic improvement in terms of playing disciplined, sound technique football," coach Jim Harbaugh said. "So, it's a great job by the fellas in that regard. Execution's been good, getting better and you keep seeing that we can, that there's even, you play good football and there's room for improvement."

Both quarterbacks figure to be tested, with Newton going up against a San Francisco defense that ranks fourth in opponent passer rating (75.3). Colin Kaepernick has rushed 18 times for 122 yards and three scores in his last two games, but Carolina has given up a total of 43 yards on 21 carries to opposing quarterbacks this year with no TDs.

Frank Gore, second in the NFL in rushing since Week 3 with 558 yards, is facing the league's second-best run defense (79.1 ypg).

While the 49ers' passing game has floundered -- they rank last in yardage -- Kaepernick should be helped by Mario Manningham's expected season debut. Manningham, out since suffering a knee injury last December, was second on the team last season with 42 receptions for 449 yards.

Fellow receiver Michael Crabtree was cleared to practice Tuesday, but he's likely still a few weeks away from playing after tearing his Achilles in May.

It's not clear whether Aldon Smith will play after he rejoined the team this week following a stint at an inpatient treatment center for substance abuse. Smith, arrested in September on suspicion of DUI and for possession of marijuana, has 4 1/2 sacks and 18 tackles in three games.

Carolina has won seven of the last nine meetings, including three of four in San Francisco. The teams haven't played since a 23-20 Panthers win Dec. 24, 2010, though Gore totaled 159 yards and a TD on 23 touches.

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Cam Newton posted his lowest Total QBR in a win in his career (19.3). The Panthers had been 1-12 in games Newton started and his Total QBR was below 40.0. The only other win was against the Jaguars.

The 49ers had four yards of offense on 14 fourth-quarter plays against the Panthers (fewest fourth-quarter yards since 2008 vs Bills). Kaepernick was 2-of-9 passing with an interception, and was sacked three times in the fourth quarter Sunday. He has the third-lowest fourth-quarter Total QBR in the NFL this season.

Lowest 4th-Quarter Total QBR This Season

- Cam Newton was 6-for-8 for 63 yards on third down in the second half after going 1-4 with an interception on third down in the first half.
- Newton was 6-for-8 for 63 yards when targeting Steve Smith in the second half, including 4-for-5 on third down. Newton only targeted Smith once in the first half.

- The Panthers sacked Kaepernick a season-high six times, with four coming when rushing four or fewer defenders. Kaepernick hadn't taken more than three total sacks in a game this season.
- Kaepernick didn't record one scramble Sunday, his first game this season without one. When Kaepernick did escape the pocket, he was 0-for-4 with two sacks.
- The 49ers were limited to 44 yards after contact on 32 rushes and receptions Sunday, their lowest of the season. 12 of the 44 yards came on one Frank Gore rush.
- The 49ers gained only 43 yards after the catch on 11 receptions. The 3.9 average yards after the catch was the lowest for the 49ers this season.

Colin Kaepernick was 0-for-6 on throws deeper than 10 yards downfield, including a game-ending interception. It is the first time in his career Kaepernick hasn't completed a deep pass with multiple attempts. The Panthers' defense is now tied with the Patriots for the most interceptions on deep passes (nine).